使用OpenSSL生成SANs證書實操

张疯牛發表於2024-10-30

當初：

原來的x.509證書，生成就一行程式碼，非常方便：

openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout key.pem -out cert.pem

然後按照提示輸入機構和dns資訊即可。

然而：

最近在開發一個websocket專案時，需要使用wss協議，在機器A（win7）上除錯沒問題，在機器B（win10+go1.22.3）上除錯，報錯：

PS E:\zjw\golang\ws> go run ws/server1wss/client
2024/10/30 15:45:37 Error connecting to server: x509: certificate relies on legacy Common Name field, use SANs instead　

經查，go1.15以後的版本廢棄了依賴Common Name欄位的x509證書，必須使用SANs證書。SANs是Subject Alternate Names的簡稱，它支援新增多個域名，允許將多個域名寫入同一個證書中，這樣就可以保護多個域名，從而降低了運維人員的管理成本，提高了證書管理效率。

採用如下方法建立證書：

1.首先安裝openssl。步驟略。

2.建立私鑰：

PS E:\zjw\ca_fsd>  openssl genrsa -des3 -out fusude.com.key 2048

3. 生成CSR

PS E:\zjw\ca_fsd> openssl req -new -key fusude.com.key -out fusude.com.csr
Enter pass phrase for fusude.com.key:
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [AU]:CN
State or Province Name (full name) [Some-State]:hebei
Locality Name (eg, city) []:shijiazhuang
Organization Name (eg, company) [Internet Widgits Pty Ltd]:fusude
Organizational Unit Name (eg, section) []:dept
Common Name (e.g. server FQDN or YOUR name) []:zjw
Email Address []:zjw@fusude.com

Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:*********
An optional company name []:fusude

4. 從秘鑰中刪除密碼（特別提示：密碼要用到，另外記好！）

PS E:\zjw\ca_fsd> cp fusude.com.key fusude.com.key.org
PS E:\zjw\ca_fsd> openssl rsa -in fusude.com.key.org -out fusude.com.key

5. 為SAN證書建立config file，名字無所謂，例如叫v3.txt，內容如下。注意subjectAltName裡，設定你需要的DNS Name

subjectKeyIdentifier = hash
authorityKeyIdentifier = keyid:always,issuer:always
basicConstraints = CA:TRUE
keyUsage = digitalSignature, nonRepudiation, keyEncipherment, dataEncipherment, keyAgreement, keyCertSign
subjectAltName = DNS:fusude.com, DNS:*.fusude.com
issuerAltName = issuer:copy

6. 建立自簽名證書：

PS E:\zjw\ca_fsd> openssl x509 -req -in fusude.com.csr -signkey fusude.com.key -out fusude.com.crt -days 3650 -sha256 -extfile v3.txt
Signature ok
subject=C = CN, ST = hebei, L = shijiazhuang, O = fusude, OU = dept, CN = zjw, emailAddress = zjw@fusude.com
Getting Private keys
生成的檔案fusude.com.crt即為我們需要的SANs證書。

7. 還可以轉換為pfx或pem格式：

PS E:\zjw\ca_fsd> openssl pkcs12 -export -out fusude.com.pfx -inkey fusude.com.key -in fusude.com.crt
Enter Export Password:
Verifying - Enter Export Password:

PS E:\zjw\ca_fsd> openssl pkcs12 -export -out fusude.com.pem -inkey fusude.com.key -in fusude.com.crt
Enter Export Password:
Verifying - Enter Export Password:

8. 證書的使用不展開論述。感謝觀看。

　　

感謝Azure Lei Zhang的部落格 ： Azure Application Gateway (6) 使用OpenSSL建立SAN證書

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